OVERVIEW: What every practitioner needs to know

Are you sure your patient has appendicitis? What are the typical findings for this disease?

Acute appendicitis is the most common abdominal pediatric surgical emergency. There are approximately 70,000 cases of pediatric appendicitis each year. Despite its frequency, appendicitis remains a diagnostic challenge when patients do not present with the typical history of peri-umbilical pain relocating to the right lower quadrant and focal peritonitis in the right lower quadrant. Those diagnosed with appendicitis require appendectomy, which is almost universally performed laparoscopically.

Typical Findings:

Peri-umbilical pain relocating to the right lower quadrant (McBurney's point)

Fever

Nausea and vomiting

Anorexia

Elevated white blood cell count

Involuntary guarding, rebound tenderness or other signs of peritonitis on physical exam

Important points for pain associated with appendicitis; the pain is usually constant, worsens with time and movement.

What other disease/condition shares some of these symptoms?

Appendicitis is one of the most common indications for surgery in children, yet it remains a diagnostic challenge to the practitioner. In males there are few other surgical diseases which mimic appendicitis though gastroenteritis, mesenteric adenitis or lower GI irritation should all be considered. In females, however, the diagnostic challenge increases, as there are many obstetrical and gynecological conditions that may mimic appendicitis. Ovarian pathology (such as cysts or torsion), endometriosis, and pregnancy must all be entertained in the differential diagnosis. In both boys and girls urinary tract infections or kidney stones can also mimic appendicitis and must be ruled out prior to arriving at the diagnosis of appendicitis.

What caused this disease to develop at this time?

Most believe occlusion of the lumen of the appendix is the inciting event. This may be from fecal material such as a fecalith. Luminal obstruction may also result from lymphoid hyperplasia secondary to bacterial or viral illness. The presumed mechanism is swelling of the lymph nodes in Peyer's patches within the mesentery of the terminal ileum, which in turn obstructs drainage from the appendiceal lumen. Stasis of the luminal contents leads to bacterial overgrowth and swelling of the appendix. This results in increased pressure and impaired venous drainage, which in turn leads to visceral pain which manifests as the typical peri-umbilical pain.

As the infection progresses and the appendix exudes an inflammatory exudate, the peritoneal lining itself becomes inflamed which results in right lower quadrant pain and peritoneal findings on physical exam.

What laboratory studies should you request to help confirm the diagnosis? How should you interpret the results?

Complete blood count with differential and urinalysis are mandatory prior to confirming the diagnosis of appendicitis. Appendicitis is rare without an elevated white blood cell count and left shift, though a normal white blood cell count does not exclude the diagnosis of appendicitis. Urinary infection or renal stones may mimic appendicitis and must be ruled out prior to proceeding to surgery.

Would imaging studies be helpful? If so, which ones?

Ultrasound and computed tomography (CT) scan can be utilized in the diagnosis of appendicitis. Ultrasound is highly dependant on experience and the results can be difficult to interpret. CT scan is highly sensitive and specific, but carries the risks of ionizing radiation. Recently, magnetic resonance imaging (MRI) has been used with high sensitivity and specificity. The previous downside to this modality was the need for sedation as patient motion leads to image artefact. Many institutions now use imaging protocols that preclude the need for sedation in children as young as 5 years of age.

Confirming the diagnosis

Because of concern about radiation exposure in children, the use of diagnostic ultrasound has been increasing. A protocol from the author's institution used to guide the workup of appendicitis is included (See Figure 1).

Figure 1.

Appendicitis workup algorithm

If you are able to confirm that the patient has appendicitis, what treatment should be initiated?

Once the diagnosis of appendicitis is made, or there is a high suspicion, oral intake should be discontinued and maintenance IV fluids and broad spectrum antibiotics should instituted immediately. Antibiotics should cover gram positive and negative aerobic organisms as well as anaerobes.

The child may require fluid resuscitation if there has been a prolonged period of reduced oral intake and vomiting. Surgical consultation is essential after the diagnosis of appendicitis and often helpful during the work-up. Physical examination by an experienced set of hands can be the most sensitive and specific means of arriving at the correct diagnosis. In atypical or confusing scenarios, observation and serial abdominal exams may be prudent.

The definitive treatment for appendicitis is appendectomy. This is most commonly performed with laparoscopy though an open procedure may be required. Approximately one third of patients with appendicitis will present with ruptured appendicitis. This increases the post-operative risk of bowel obstruction and abscess formation. Some patients may already have developed an abscess or a phlegmon so severe that it limits the ability to perform a safe laparoscopic appendectomy. These patients may be treated with percutaneous abscess drain and/or IV antibiotics prior to proceeding with laparoscopic appendectomy.

There is recent interest in examining the role of non-operative therapy for appendicitis. In patients with early simple appendicitis there is approximately a 75% success rate with antibiotic therapy alone. However, there are no long-term follow-up data to suggest this treatment modality is equivalent to appendectomy and therefore, not recommended as a standard of care.

What are the adverse effects associated with each treatment option?

Laparoscopic and open appendectomy are both associated with the standard risks of abdominal surgery; mainly pain, bleeding, infection, damage to other intra-abdominal organs and the risk of future adhesive bowel obstruction. Appendectomy also carries the risk of post-operative abscess formation requiring additional drainage (either percutaneously or in the operating room) and antibiotic treatment. The risk of post-operative abscess formation is higher if the appendix has ruptured.

Other risks include the risk of recurrent appendicitis. This is rare and occurs when the remaining appendiceal stump is too long. This is more likely to occur if appendectomy is performed in a highly inflamed operative field, and the base of the appendix is not easy to identify.

What are the possible outcomes of appendicitis?

If left untreated, appendicitis can progress to bacteremia, sepsis, multiple organ failure and death. Fortunately, this is very rare. Patients presenting with non-perforated appendicitis who undergo uncomplicated laparoscopic appendectomy usually spend only a night in the hospital. These patients can expect to recover fully within a couple of weeks. Patients presenting with ruptured appendicitis may have a longer hospital course and convalescence, but can expect to recover without sequelae.

What causes this disease and how frequent is it?

The cause of appendicitis is luminal obstruction as previously described.

There are approximately 70,000 cases of pediatric appendicitis every year. The incidence from birth to 4 years old is 1-2 cases per 10,000 children per year. The incidence increases to 25 per 10,000 children per year from 10-17 years of age. Overall 7% of the population in the United States will have their appendix removed. There is a 2:1 male:female ratio. The incidence is higher in developed countries for unknown reasons.

How do these pathogens/genes/exposures cause the disease?

See 'What caused this disease to develop at this time'.

Other clinical manifestations that might help with diagnosis and management

What complications might you expect from the disease or treatment of the disease?

Left untreated, appendicitis can progress to bacteremia, sepsis, multiple organ failure and death. Fortunately, this is exceedingly rare. The most common complications after appendicitis and appendectomy are post operative abscess and adhesive bowel obstruction. Abscess may be treated with antibiotics, percutaneous drainage and rarely surgery. Bowel obstruction may be treated conservatively with bowel decompression or rest. However, if this fails the patient may require surgery to lyse obstructing adhesions.

Are additional laboratory studies available; even some that are not widely available?

How can appendicitis be prevented?

There is no known means of preventing appendicitis.

What is the evidence?

The management of appendicitis with appendectomy is well established. While this remains the gold standard, recently there has been renewed interest in non-operative therapy. At this time however, non-operative therapy cannot be recommended as equivalent to appendectomy as there are no good long-term follow-up data. There may be some variation in care with regards to which specific antibiotics are used and as to the necessity of interval appendectomy. Lastly, MRI has emerged as a viable alternative to CT scan when imaging patients with suspected appendicitis. The following articles review these issues.

Ongoing controversies regarding etiology, diagnosis, treatment

There are no significant controversies in the management of appendicitis and the gold standard is appendectomy. In cases of perforated appendicitis with well formed abscess which are treated with percutaneous biopsy and antibiotics, there is some controversy over the need for interval appendectomy. This is dependant on each individual surgeon and there is little evidence for or against interval appendectomy to make any recommendation.

**The original author for this chapter was Dr. David Partrick. The chapter was revised by Drs. Jonathan P. Roach and David Partrick.